1. Field of the Invention
The present invention relates to a shielded cable connecting structure applied to various electrical equipment such as motors in an electrical vehicle, and more particularly to a shield cable connecting structure which provides both a shielded connection and waterproofing.
2. Description of the Related Art
When making connections of high-voltage cables to motors or making connections to control signal cables in electrical vehicles, for example, it is necessary to provide both electromagnetic shielding and waterproofness. This electromagnetic shielding is done to avoid unstable motor operation caused by various types of noise, and waterproofing is done to prevent the intrusion of corrosion damage to electrical contact parts by the intrusion of rain moisture into the motor via the shielded cable.
A shielded cable connecting structure that provides electromagnetic shielding and waterproofing is disclosed in the Japanese laid open patent application publication H10-112924, which is illustrated in FIG. 1 and FIG. 2A and 2B. As shown in FIG. 1, the shielded cable connecting structure makes connection to the braid 6a of the shielded cable 6, via a substantially cylindrical housing 3, a bolt 4, and a shield connection ring 5 that serves as a shield connection member within a cable insertion hole 2a in the motor case 2 of the main equipment to which connection is made. That is, the outer peripheral surface 3a of the housing 3 is fitted into the cable insertion hole 2a of the motor case, a mounting flange 3b used for this purpose being held fast by the bolt 4, so that the housing 3 through which the shielded cable 6 is inserted in mounted to the motor case 2.
As shown in FIG. 2A and FIG. 2B, the braid 6a of the shielded cable 6, which is inserted into the housing 3 is folded back onto a peripheral depression at the end of the housing 3, this folded-back braid 6a being sandwiched by the shield connection ring 5 that is fitted over the peripheral depression 3c at the end of the housing 3. This shield connection ring 5 is made of a metal having good resilience, and is formed so to have a gap opening in its center, the folded-back braid 6a of the shielded cable 6 being freely held in place to prevent the pulling out thereof, by a plurality of spring places 3a and a fang piece 5b. Additionally, each of the spring pieces 5a of the shield ring 5 is in resilient contact with the cable insertion hole 2a of the motor case 2. According to this configuration, the braid 6a of the shielded cable 6 is grounded via the motor case 2.
The annular groove 3d formed at the outer peripheral surface 3a of the housing 3 has an O-ring 7 that fitted therein, which provide an intimate seal between the housing 3 and the motor case 2. Additionally, a substantially cylindrically shaped waterproof cover 8 is inserted between the outer insulation covering 6b of the shielded cable 6 and the housing 3. The above-noted O-ring 7 and waterproof cover 8 reliably prevent the intrusion of rain moisture into the motor case 2 from the outside. The shielded cable 6, which is inserted through a corrugated tube 9, is inserted into the cable insertion hole 2a of the housing 2. Additionally, the inner conductor 6d which is exposed from the inner insulation covering 6c of the shielded cable 6 has crimped onto it a connection terminal (not shown in the drawing) that makes connection with a motor terminal (not shown in the drawing).
Art similar the above-noted shielded cable connecting structure is disclosed, for example, in the Japanese laid-open patent application publication H9-180824.
In the above-described shielded cable connecting structure 1, however, because the spring force of the shield connection ring 5 in used to make a connection between the cable insertion hole 2a of the motor case 2 and the braid 6a of the shielded cable 6, fatiguing of the spring characteristics of the shield connection ring 5 with the passage of time and other phenomena lead to the danger of a deterioration of the shielding characteristics Additionally, because the same surface of the cable insertion hole 2a of the motor case 2 serves as the surface that shields the braid 6a and the waterproofing surface that makes contact with the O-ring 7, when mounting the housing 3 to the motor case using the bolt 4, there was a danger of damaging this waterproofing surface, thereby causing a worsening of waterproofness. Additionally, because the housing 3 is mounted to the motor case 2 via the flange 3b and the bolt 4, it is absolutely necessary to provide sufficient space for mounting, thereby causing an increase in size of the overall structure.
Accordingly it is an object of the present invention to solve the problems described above in the related art, by providing a shielded cable connecting structure that provides reliable shield connection and waterproofness, and which also enables an overall savings in space.